1. Field of the Invention
The present invention relates generally to methods for producing tetrasubstituted acrylic esters.
2. Description of the Background Art
Acrylic esters can be used as intermediates in many different and varied organic synthesis procedures in which compounds which possess particular qualities and characteristics can be produced. In particular, stereospecific acrylic esters can be especially useful as intermediates in these organic synthesis procedures.
For example, an (E)-tetrasubstituted acrylic ester of the formula ##STR2## where Ph represents a phenyl group, Me represents a methyl group, and Et represents an ethyl group, can be converted into d-Oxyphene as taught by Erickson, T. J., J. Org. Chem., Vol. 51, p. 934-5 (1986). The compound d-Oxyphene, in turn, can be converted into d-propoxyphene, a compound which possesses good analgesic qualities. Pohland, A., and Sullivan, H. R., J. Am. Chem. Soc., Vol. 77, p. 3400 (1955).
Furthermore, (E)-tetrasubstituted acrylic esters can be converted into 2,3 disubstituted-2-cyclopenten-1-ones. Mathew, J., J. Org. Chem., Vol. 55, p. 5294-5297 (1990); Mathew, J., J. Chem. Soc. Chem. Commun., p. 684-6 (1990). These cyclopentenones are valuable in the perfume and pharmaceutical industries.
Accordingly, it is desirable to synthesize (E)-tetrasubstituted acrylic esters in high yield and with good stereospecificity so that these esters can be used as intermediates in the synthesis of compounds such as d-propoxyphene and cyclopentenones.
Organic synthesis of tetrasubstituted acrylic esters can occur through a number of different reaction mechanisms or routes. Among these mechanisms or routes are the Wittig reaction (Wadsworth, W. J., Organic Reactions, Chp. 2, p. 73-253 (1977)) and the Peterson reaction (Hudrlik, P., and Peterson, D., J. Am. Chem. Soc., Vol. 97, p. 1464 (1975)). The Wittig reaction comprises reacting a phosphorane with a compound containing a carbonyl group so as to obtain an unsaturated compound. The Peterson reaction is essentially an elimination reaction in which .beta.-hydroxyalkylsilanes are reacted with metallic hydrides (e.g., diisobutylaluminum hydride) to produce an olefin.
Previously, methods in which olefins have been synthesized, such as the Wittig and Peterson reactions, have yielded tetrasubstituted olefins with poor stereospecificity. Therefore, methods are needed for synthesizing stereospecific tetrasubstituted acrylic esters quickly, efficiently and with good stereospecificity.